US7800027B2 - Method of water temperature calibration for electric kettle - Google Patents

Method of water temperature calibration for electric kettle Download PDF

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Publication number
US7800027B2
US7800027B2 US11/632,098 US63209805A US7800027B2 US 7800027 B2 US7800027 B2 US 7800027B2 US 63209805 A US63209805 A US 63209805A US 7800027 B2 US7800027 B2 US 7800027B2
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Prior art keywords
temperature
heating
water
recited
microprocessor
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US11/632,098
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US20080302780A1 (en
Inventor
Mohan Zhang
Yaolun Wang
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Crastal Technology Shenzhen Co Ltd
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Crastal Technology Shenzhen Co Ltd
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Assigned to CRASTAL TECHNOLOGY (SHENZHEN) CO., LTD. reassignment CRASTAL TECHNOLOGY (SHENZHEN) CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: WANG, YAOLUN, ZHANG, MOHAN
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Classifications

    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J27/00—Cooking-vessels
    • A47J27/21—Water-boiling vessels, e.g. kettles
    • A47J27/21008—Water-boiling vessels, e.g. kettles electrically heated
    • A47J27/21058—Control devices to avoid overheating, i.e. "dry" boiling, or to detect boiling of the water
    • A47J27/21091—Control devices to avoid overheating, i.e. "dry" boiling, or to detect boiling of the water of electronic type
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/1917—Control of temperature characterised by the use of electric means using digital means
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00—Control of temperature
    • G05D23/19—Control of temperature characterised by the use of electric means
    • G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
    • G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor

Definitions

  • the present invention relates to an electric kettle, and more particularly to a method of water temperature calibration for an electric kettle, which is adapted to accurately determine the temperature of the boiling water in the electric kettle and to cut off the heating power when the water is boiled.
  • the electric kettle has brought many conveniences for people in their living and work.
  • the traditional method for electric kettle to determine and control the boiling water is to apply a “steam” switch made of dual metal materials to switch off the power of the heating source. Accordingly, the amount of steam generated by the boiling water must be enough to trigger the switch so as to cut off the power.
  • a steam channel In order to guide the steam to communicate with the switch, a steam channel must be additionally formed to let the steam entering into the switch. Therefore, the switch not only complicates the original structural configuration of the electric kettle but also fails to keep the aesthetic appearance of the electric kettle. Importantly, the switch is not sensitive enough to detect the water at the boiling point to cut off the power simultaneously.
  • An alternative calibrating method is to provide a temperature sensor to detect the water temperature such that when the water reaches a preset temperature threshold, the temperature sensor triggers the switch to turn off the power of the heating source.
  • the major drawback of the temperature sensor is that the temperature sensor cannot be used when the electric kettle is operated at a location with higher altitude. It is known that the water cannot be reached its boiling point at the high altitude location. Therefore, the heating source will keep heating up the water when the water is boiled. In other words, it is unsafe for the user to operate the temperature sensor type electric kettle at the high altitude location. In addition, such temperature sensor has an error that the temperature sensor cannot accuracy detect the actual water temperature. Therefore, the electric kettle may either boil the water without cutting off the power or cut the power without fully boiling the water.
  • a main object of the present invention is to provide a method of water temperature calibration for an electric kettle, which is adapted to accurately determine the temperature of the boiling water and to cut off the power of the heating source at the same time.
  • the present invention provides a method of water temperature calibration for an electric kettle containing a predetermined volume of water, comprising the steps of:
  • the cycle of the temperature rate change is preset by the microprocessor.
  • the cycle is determined by the microprocessor that the microprocessor has an input terminal connecting to a gain resistor of the electric kettle to obtain a value of the heating power thereof, wherein the cycles in responsive to different heating powers are saved in a sorting manner.
  • control circuit When the control circuit receives the control signal from the microprocessor, the control circuit cuts off the power of the heating source to stop heating the water.
  • the microprocessor processes the interior temperature, which is obtained from either the water temperature, the temperature of the heating point contacting with the water, or the temperature of the interior wall of the kettle body, and compare the current cycle of the interior temperature with the previous cycle of the interior temperature.
  • the microprocessor processes the water temperature and the temperature rate change thereof for calibration.
  • the meaning of “the temperature rate change is minimized” is defined the current cycle of rate change of the temperature is relatively small in comparison with the previous cycle of rate change of the temperature. In other words, it means that the difference is the minimum temperature rate change between said current cycle and said previous cycle.
  • the microprocessor presets a rate change threshold that when the temperature rate change is smaller than the rate change threshold, the microprocessor sends out the control signal to the control circuit.
  • the microprocessor When the control circuit cuts off the power of the heating source, the microprocessor erases the saved values of all temperature rate change and comparing data.
  • the control circuit When the control circuit activates the heating source for heating up the water, the temperature sensor is automatically activated to detect the interior temperature of the electric kettle. When the water temperature, the temperature of the heating point contacting with the water, or the temperature of the interior wall of the kettle body is larger than a preset starting temperature threshold, the microprocessor will start processing the temperature rate change for calibration.
  • the present invention incorporates with the microprocessor to determine the temperature rate change. Accordingly, during the heat up process, the temperature rate change is determined to evaluate whether the water in the electric kettle is boiling or not in order to send the control signal to the control circuit to cut off the power of the heating source. Therefore, the present invention is adapted to accurately determine the temperature of the boiling water in the electric kettle and simultaneously to cut off the heating power when the water is boiled, such that the user is able to use the electric kettle safely.
  • the present invention applies such properties of water to calibrate whether the water is boiled in the electric kettle. Accordingly, the present invention provides a method of water temperature calibration for an electric kettle, comprising the following steps.
  • control circuit When the control circuit electrically connects to the heating source, detect the interior temperature in the electric kettle via the temperature sensor, wherein the interior temperature is measured by either the water temperature, the temperature of the heating point of the heating source contacting with the water, or the temperature of the interior wall of a kettle body of the electric kettle.
  • the cycle of temperature rate change is preset in the microprocessor.
  • the present invention applies NTC (negative temperature coefficient) heat-variable resistor as the temperature sensor, which is negatively correlated to temperature.
  • the direct current loading on the NTC heat-variable resistor is in responsive to the water temperature, wherein the microprocessor comprises an A/D (analogy to digital) converter converting the signal from the NTC heat-variable resistor into a corresponding digital data.
  • the digital data which is inversely correlated to the water temperature, denotes the water temperature of the electric kettle.
  • the method of determining the temperature rate change comprises the steps of setting the digital data of the current cycle of water temperature as subtrahend, setting the digital data of the previous cycle of water temperature as minuend, determining the difference between the previous cycle of water temperature and the current cycle of water temperature to determine the temperature rate change.
  • the temperature rate change is in responsive to the heating power, the water capacity of the electric kettle and the water level therein, wherein the heating power and the water capacity are constant. Furthermore, after taking the water level from low to high into account, the temperature rate change becomes constant for the particular electric kettle.
  • a plurality of different voltage-dividing resistors are set at the terminal of the A/D converter of the microprocessor to obtain inquired values for determining the temperature rate change. Therefore, different resistors with different resistances thereof are set at the terminal of the A/D converter of the microprocessor.
  • the microprocessor presets the lowest temperature rate change threshold such that when the temperature rate change is smaller than the lowest temperature rate change threshold, the microprocessor sends out the control signal to the control circuit to cut off the power of the heating source so as to stop heating up the water.
  • the electric kettle has a heating power less than 1200 W that the electric kettle is adapted to heat up the water slowly.
  • the electric kettle comprises a NTC (negative temperature coefficient) heat-variable resistor, a microprocessor CPU having multi-path A/D conversion, and the control circuit having a transistor connecting to the input terminal of the microprocessor.
  • the temperature sensor detects the interior temperature of the electric kettle.
  • the microprocessor starts to determine the interior temperature and to save the interior temperature and the temperature rate change. Accordingly, the cycle is set as 10 seconds.
  • the electric kettle has a heating power of 3000 W that the electric kettle is adapted to heat up the water rapidly.
  • the electric kettle comprises a NTC (negative temperature coefficient) heat-variable resistor, a microprocessor CPU having multi-path A/D conversion, and the control circuit having a transistor connecting to the input terminal of the microprocessor.
  • the temperature sensor detects the interior temperature of the electric kettle.
  • the microprocessor starts to determine the interior temperature and to save the interior temperature and the temperature rate change. Accordingly, the cycle is set as 2 seconds.
  • the microprocessor through the digital data of the A/D converter, determines the current cycle of the interior temperature in current 2 seconds as subtrahend and the previous cycle of the interior temperature in previous 2 second as minuend. Then, the microprocessor determines the difference between the previous cycle of water temperature and the current cycle of water temperature to determine the temperature rate change. When the temperature rate change is smaller than or equal to 1, the temperature rate change inclines to be flattened. When the lowest value of the current cycle of the temperature rate change is smaller than 1, the microprocessor sends out the control signal to the control circuit to cut off the power of the heating source so as to stop heating up the water. At the same time, the process returns back to its initial state and all the values including the temperature rate change and the intermediate calibrating data determined by the microprocessor are erased.
  • the electric kettle has a heating power less than 2000 W that the electric kettle is adapted to heat up the water gradually.
  • the electric kettle comprises a NTC (negative temperature coefficient) heat-variable resistor, a microprocessor CPU having multi-path A/D conversion, and the control circuit having a transistor connecting to the input terminal of the microprocessor.
  • the temperature sensor detects the interior temperature of the electric kettle.
  • the microprocessor starts to determine the interior temperature and to save the interior temperature and the temperature rate change. Accordingly, the cycle is set as 6 seconds.
  • the microprocessor through the digital data of the A/D converter, determines the current cycle of the interior temperature in current 6 seconds as subtrahend and the previous cycle of the interior temperature in previous 6 second as minuend. Then, the microprocessor determines the difference between the previous cycle of water temperature and the current cycle of water temperature to determine the temperature rate change. When the temperature rate change is smaller than or equal to 1, the temperature rate change inclines to be flattened. When the lowest value of the current cycle of the temperature rate change is smaller than 1, the microprocessor sends out the control signal to the control circuit to cut off the power of the heating source so as to stop heating up the water. At the same time, the process returns back to its initial state and all the values including the temperature rate change and the intermediate calibrating data determined by the microprocessor are erased.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Food Science & Technology (AREA)
  • Cookers (AREA)
US11/632,098 2005-09-10 2005-09-10 Method of water temperature calibration for electric kettle Active 2026-07-29 US7800027B2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2005/001455 WO2007028282A1 (fr) 2005-09-10 2005-09-10 Procede de determination de l'ebullition de l'eau dans des bouilloires electriques

Publications (2)

Publication Number Publication Date
US20080302780A1 US20080302780A1 (en) 2008-12-11
US7800027B2 true US7800027B2 (en) 2010-09-21

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US11/632,098 Active 2026-07-29 US7800027B2 (en) 2005-09-10 2005-09-10 Method of water temperature calibration for electric kettle

Country Status (5)

Country Link
US (1) US7800027B2 (fr)
EP (1) EP1923764B1 (fr)
AU (1) AU2005336311B2 (fr)
ES (1) ES2393789T3 (fr)
WO (1) WO2007028282A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8900857B2 (en) 2008-06-18 2014-12-02 Leica Biosystems Melbourne Pty Ltd Devices and methods for tissue handling and embedding
CN101669763B (zh) * 2008-09-09 2011-07-27 广东德豪润达电气股份有限公司 一种即热式电水壶及其控制方法
CN102063137B (zh) * 2010-11-09 2014-07-09 美的集团股份有限公司 一种电子温控水壶的控制方法
US9134788B2 (en) * 2011-12-29 2015-09-15 Intel Corporation Method, apparatus, and system for energy efficiency and energy conservation including detecting and controlling current ramps in processing circuit
CN105326386B (zh) * 2015-11-23 2017-12-01 珠海格力电器股份有限公司 水温沸点判断方法和装置以及电热水壶
EP3335600B1 (fr) * 2016-07-27 2021-02-17 Guangdong Midea Consumer Electrics Manufacturing Co., Ltd. Procédé de commande anti-débordement pour robot alimentaire ménager et robot alimentaire ménager
CN112099550B (zh) * 2020-08-18 2021-11-26 宁波方太厨具有限公司 一种水加热电器的温度控制方法
CN113475933B (zh) * 2021-07-27 2022-04-15 珠海格力电器股份有限公司 提升保温效果的加热控制方法、装置、养生壶及存储介质

Citations (4)

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US5324917A (en) * 1989-09-15 1994-06-28 Compagnie Europeenne Pour L'equipement Menager-Cepem Device and method for regulation the temperature and/or power of a cooking apparatus
US6118105A (en) * 1999-07-19 2000-09-12 General Electric Company Monitoring and control system for monitoring the boil state of contents of a cooking utensil
US6155159A (en) * 1999-02-19 2000-12-05 Seb S.A. Safety device for electric cooking appliance having a removable bowl
US7279660B2 (en) * 2003-02-06 2007-10-09 Edgecraft Corporation Apparatus for brewing beverages

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AU633042B2 (en) * 1989-01-26 1993-01-21 Otter Controls Limited Controls for electrically powered heating elements
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GB2298723B (en) * 1995-02-20 1998-10-28 Simatelex Manuf Co Thermopots
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Publication number Priority date Publication date Assignee Title
US5324917A (en) * 1989-09-15 1994-06-28 Compagnie Europeenne Pour L'equipement Menager-Cepem Device and method for regulation the temperature and/or power of a cooking apparatus
US6155159A (en) * 1999-02-19 2000-12-05 Seb S.A. Safety device for electric cooking appliance having a removable bowl
US6118105A (en) * 1999-07-19 2000-09-12 General Electric Company Monitoring and control system for monitoring the boil state of contents of a cooking utensil
US7279660B2 (en) * 2003-02-06 2007-10-09 Edgecraft Corporation Apparatus for brewing beverages

Also Published As

Publication number Publication date
AU2005336311B2 (en) 2009-12-24
EP1923764A4 (fr) 2008-11-12
EP1923764A1 (fr) 2008-05-21
AU2005336311A1 (en) 2007-03-15
WO2007028282A1 (fr) 2007-03-15
ES2393789T3 (es) 2012-12-28
US20080302780A1 (en) 2008-12-11
EP1923764B1 (fr) 2012-08-22

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